I. Field of the Invention
The present invention relates to a sensor and related method for measuring the position and orientation (POSE) of an object.
II. Background Information
To measure the actual POSE of robotic and effectors and the like, various sensors have been proposed. For example, one proposed sensor contemplates the utilization of a target cube positioned on the end effector of a robot. The target cube is used in connection with a hollowed-out tube detector which contains in each wall thereof a trio of contact dial gauges. The robot end effector target cube is moved into contact with the gauges in the interior of the hollow cube detector. Upon contact with the gauges, the actual position and orientation (POSE) of the target cube may be calculated from the output of the gauges and compared against the expected position of the target cube.
Such prior art sensors suffer from the obvious defect of requiring physical contact between a target cube on the end effector and the detector cube. Such contact may actually alter the position of the end effector and thereby introduce error into the resultant POSE measurements.
Non-contact optical sensing systems have been developed to determine position but not both position and orientation. Thus, such optical systems can determine where the end effector of a robotic device is, but cannot determine the orientation of that and effector and, hence, can provide only limited information upon which robotic performance may be improved.
Non-contact sensing devices employing eddy current detection are also known. However, like the known optical systems, such eddy current systems can only measure the position of the face of a target cube and then, can only measure that position if surfaces of the target cube are oriented approximately parallel to the surfaces of the detector cube in which the eddy current device is mounted. Accordingly, such systems have severe limitations in that if the target cube was not moved accurately into the detector cube in an approximately parallel orientation, substantial error is incurred in the resultant position measurement.
It is, accordingly, a primary object of the subject invention to provide a non-contact sensor which accurately measures both the position and orientation of an object, such as the end effector of a robotic device.
A further object of the subject invention is to provide such a sensor which does not require any electronic parts to be mounted on the object to be measured and, therefore, causes no loading to the object and eliminates the need to provide an electrical interface to the object.
A further object of the subject invention is to provide a sensor which measures all six degrees of freedom of a standard commercial manipulator and effector with substantial accuracy and range of measurement in a relatively inexpensive manner.
Additional objects and advantages of the invention will be set forth in the description which follows and will, in part, be obvious from the description or may be learned by practice of the invention.